sedimentary
Yellow Jasper (Chert)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to brownish-orange, Luster: Waxy to dull, Structure: Cryptocrystalline, Fracture: Conchoidal
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to brownish-orange, Luster: Waxy to dull, Structure: Cryptocrystalline, Fracture: Conchoidal
Formation & geological history
Formed from the accumulation of silica-rich microfossils or volcanic ash that undergoes lithification through pressure and heat, often colored by iron oxides (goethite/limonite).
Uses & applications
Used primarily in lapidary arts for cabochons, beads, and decorative carvings; also used as landscaping gravel or for ornamental display.
Geological facts
Jasper is an opaque variety of chalcedony. The yellow variety is specifically associated with the presence of iron hydroxides. It has been used for millennia by humans for both tools and spiritual amulets.
Field identification & locations
Identify by its waxy texture, opacity (it will not let light pass through like quartz), and its inability to be scratched by a steel knife. Commonly found in riverbeds and coastal areas worldwide.
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